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The Cross-Vane,W-Weir and J-Hook Vane Structures...Their
<br /> Description,Design and Application for Stream Stabilization and River Restoration
<br /> D. L. Rosgen, P.H.*
<br /> * Professional Hydrologist,Wildland Hydrology,Inc. 1481 Stevens Lake Road.Pagosa Springs,
<br /> Colorado 81147;PH 970-731-6100;wildlandhydrology @pagosa.net
<br /> Abstract
<br /> The descriptions,design specifications,placement locations, spacing and various applications of
<br /> Cross-Vane, W-Weir and J-Hook Vane structures are presented. These structures were
<br /> developed and subsequently applied to: 1) establish grade control, 2)reduce streambank erosion,
<br /> 3) facilitate sediment transport, 4)provide for irrigation diversion structures, 5)enhance fish
<br /> habitat, 6)maintain width/depth ratio, 7)improve recreational boating, 8)maintain river stability,
<br /> 9)dissipate excess energy, 10)withstand large floods, 11)maintain channel capacity, 12)be
<br /> compatible with natural channel design, and 13)be visually acceptable to the public.
<br /> Relations to determine the minimum size of rock for these structures are presented based on
<br /> bankfull shear stress. Drawings for each structure are provided that display appropriate use of
<br /> footers, cross-section shape, profile shape, appropriate channel locations, angles, slopes, spacing
<br /> and elevations. Velocity isovels are presented to describe changes in the distribution of energy
<br /> produced by the structures. The structures all reduce near-bank shear stress and stream power,
<br /> while increasing center channel shear stress and stream power to retain both flood-flow and
<br /> sediment transport capacity. These structures have been installed on 14 rivers with bankfull
<br /> widths varying from 9m(Lower Blanco River in Southwestern Colorado)to 150m(Bitterroot
<br /> River in Northwestern Montana) and slopes varying from 0.05 to .0003 and in bed material
<br /> ranging from cobble and gravel to sand bed streams. Since 1986,the author has restored and
<br /> monitored a wide variety of stream types involving over 48 km of rivers and evaluated various
<br /> structure performance following major floods. This monitoring has resulted in the development,
<br /> implementation and assessment of the Cross-Vane, W-Weir and 3-Hook vane structures.
<br /> Introduction
<br /> Structures in river engineering are designed to help stabilize channel boundaries. However,
<br /> monitoring their effectiveness have indicated that many structures, contrary to the intended
<br /> design, caused river instability. Structures are often selected and installed without an
<br /> understanding of sediment transport and violate the dimension,pattern and profile of the stable
<br /> river. Relations for canal design based on rigid boundary theory, clear water discharge, and
<br /> uniform flow have been implemented on natural channels,with less than effective results. Work
<br /> conducted by Leopold, et al, (1964)found that river form is associated with an integration of
<br /> eight interrelated variables,that if any one variable is changed, it sets up mutual, concurrent
<br /> adjustments of the other variables in the stream system until a new gaasi-equilibrium is reached
<br /> (stability). The eight variables are slope,width, depth,velocity, discharge,boundary roughness,
<br /> size of sediment transported,and concentration of sediment. The variables can be integrated into
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